Nutritional ketosis improves exercise metabolism in patients with very long-chain acyl-CoA dehydrogenase deficiency.

A maladaptive shift from fat to carbohydrate (CHO) oxidation during exercise is thought to underlie myopathy and exercise-induced rhabdomyolysis in patients with fatty acid oxidation (FAO) disorders. We hypothesised that ingestion of a ketone ester (KE) drink prior to exercise could serve as an alternative oxidative substrate supply to boost muscular ATP homeostasis. To establish a rational basis for therapeutic use of KE supplementation in FAO, we tested this hypothesis in patients deficient in Very Long-Chain acyl-CoA Dehydrogenase (VLCAD). Five patients (range 17-45 y; 4 M/1F) patients were included in an investigator-initiated, randomised, blinded, placebo-controlled, 2-way cross-over study. Patients drank either a KE + CHO mix or an isocaloric CHO equivalent and performed 35 minutes upright cycling followed by 10 minutes supine cycling inside a Magnetic Resonance scanner at individual maximal FAO work rate (fatmax; approximately 40% VO2 max). The protocol was repeated after a 1-week interval with the alternate drink. Primary outcome measures were quadriceps phosphocreatine (PCr), Pi and pH dynamics during exercise and recovery assayed by in vivo 31 P-MR spectroscopy. Secondary outcomes included plasma and muscle metabolites and respiratory gas exchange recordings. Ingestion of KE rapidly induced mild ketosis and increased muscle BHB content. During exercise at FATMAX, VLCADD-specific plasma acylcarnitine levels, quadriceps glycolytic intermediate levels and in vivo Pi/PCr ratio were all lower in KE + CHO than CHO. These results provide a rational basis for future clinical trials of synthetic ketone ester supplementation therapy in patients with FAO disorders. Trial registration: ClinicalTrials.gov. Protocol ID: NCT03531554; METC2014.492; ABR51222.042.14.

Dietary practices in methylmalonic acidaemia: a European survey.

Background The dietary management of methylmalonic acidaemia (MMA) is a low-protein diet providing sufficient energy to avoid catabolism and to limit production of methylmalonic acid. The goal is to achieve normal growth, good nutritional status and the maintenance of metabolic stability. Aim To describe the dietary management of patients with MMA across Europe. Methods A cross-sectional questionnaire was sent to European colleagues managing inherited metabolic disorders (IMDs) (n=53) with 27 questions about the nutritional management of organic acidaemias. Data were analysed by different age ranges (0-6 months; 7-12 months; 1-10 years; 11-16 years; >16 years). Results Questionnaires were returned from 53 centres. Twenty-five centres cared for 80 patients with MMA vitamin B12 responsive (MMAB12r) and 43 centres managed 215 patients with MMA vitamin B12 non-responsive (MMAB12nr). For MMAB12r patients, 44% of centres (n=11/25) prescribed natural protein below the World Health Organization/Food and Agriculture Organization/United Nations University (WHO/FAO/UNU) 2007 safe levels of protein intake in at least one age range. Precursor-free amino acids (PFAA) were prescribed by 40% of centres (10/25) caring for 36% (29/80) of all the patients. For MMAB12nr patients, 72% of centres (n=31/43) prescribed natural protein below the safe levels of protein intake (WHO/FAO/UNU 2007) in at least one age range. PFAA were prescribed by 77% of centres (n=33/43) managing 81% (n=174/215) of patients. In MMAB12nr patients, 90 (42%) required tube feeding: 25 via a nasogastric tube and 65 via a gastrostomy. Conclusions A high percentage of centres used PFAA in MMA patients together with a protein prescription that provided less than the safe levels of natural protein intake. However, there was inconsistent practices across Europe. Long-term efficacy studies are needed to study patient outcome when using PFAA with different severities of natural protein restrictions in patients with MMA to guide future practice.

Impact of newborn screening for very-long-chain acyl-CoA dehydrogenase deficiency on genetic, enzymatic, and clinical outcomes.

Most infants with very-long-chain acyl-CoA dehydrogenase deficiency (VLCADD) identified by newborn screening (NBS) are asymptomatic at the time of diagnosis and remain asymptomatic. If this outcome is due to prompt diagnosis and initiation of therapy, or because of identification of individuals with biochemical abnormalities who will never develop symptoms, is unclear. Therefore, a 10-year longitudinal national cohort study of genetically confirmed VLCADD patients born before and after introduction of NBS was conducted. Main outcome measures were clinical outcome parameters, acyl-CoA dehydrogenase very long chain gene analysis, VLCAD activity, and overall capacity of long-chain fatty acid oxidation (LC-FAO flux) in lymphocytes and cultured skin fibroblasts. Median VLCAD activity in lymphocytes of 54 patients, 21 diagnosed pre-NBS and 33 by NBS was, respectively, 5.4% (95% confidence interval [CI]: 4.0-8.3) and 12.6% (95% CI: 10.7-17.7; P < 0.001) of the reference mean. The median LC-FAO flux was 33.2% (95% CI: 22.8-48.3) and 41% (95% CI: 40.8-68; P < 0.05) of the control mean, respectively. Clinical characteristics in 23 pre-NBS and 37 NBS patients revealed hypoglycemic events in 12 vs 2 patients, cardiomyopathy in 5 vs 4 patients and myopathy in 14 vs 3 patients. All patients with LC-FAO flux <10% developed symptoms. Of the patients with LC-FAO flux >10% 7 out of 12 diagnosed pre-NBS vs none by NBS experienced hypoglycemic events. NBS has a clear beneficial effect on the prevention of hypoglycemic events in patients with some residual enzyme activity, but does not prevent hypoglycemia nor cardiac complications in patients with very low residual enzyme activity. The effect of NBS on prevalence and prevention of myopathy-related complications remains unclear.

Proposal for an individualized dietary strategy in patients with very long-chain acyl-CoA dehydrogenase deficiency.

BACKGROUND: Patients with very long chain acyl-CoA dehydrogenase deficiency (VLCADD), a long chain fatty acid oxidation disorder, are traditionally treated with a long chain triglyceride (LCT) restricted and medium chain triglyceride (MCT) supplemented diet. Introduction of VLCADD in newborn screening (NBS) programs has led to the identification of asymptomatic newborns with VLCADD, who may have a more attenuated phenotype and may not need dietary adjustments. OBJECTIVE: To define dietary strategies for individuals with VLCADD based on the predicted phenotype. METHOD: We evaluated long-term dietary histories of a cohort of individuals diagnosed with VLCADD identified before the introduction of VLCADD in NBS and their beta-oxidation (LC-FAO) flux score (rate of oleate oxidation) in cultured skin fibroblasts in relation to the clinical outcome. Based on these results a dietary strategy is proposed. RESULTS: Sixteen individuals with VLCADD were included. One had an LC-FAO flux score >90%, was not on a restricted diet and is asymptomatic to date. Four patients had an LC-FAO flux score <10%, and significant VLCADD related symptoms despite the use of strict diets including LCT restriction, MCT supplementation and nocturnal gastric drip feeding. Patients with an LC-FAO flux score between 10 and 90% (n = 11) showed a more heterogeneous phenotype. CONCLUSIONS: This study shows that a strict diet cannot prevent poor clinical outcome in severely affected patients and that the LC-FAO flux is a good predictor of clinical outcome in individuals with VLCADD identified before its introduction in NBS. Hereby, we propose an individualized dietary strategy based on the LC-FAO flux score.

Usefulness of open mixed nut challenges to exclude tree nut allergy in children.

BACKGROUND: To minimize the risk of accidental reactions, atopic children with multiple sensitizations to tree nuts are advised to avoid all nuts. Multiple food challenges would be needed to confirm the clinical relevance, but are too burdensome to be practical. The usefulness of open mixed nut challenges in terms of safety, reactions during challenge, tolerance of the challenge material, effect on the elimination diet and satisfaction of the parents was evaluated. FINDINGS: Open mixed nut challenges were performed in 19 children with a previous negative hazelnut challenge and long term elimination diet for tree nuts. Challenges were negative in 13 (68 %) children, in four (21 %) children (non-severe) allergic symptoms were observed. The challenges were well accepted, safe and efficient. We were able to avoid multiple nut challenges in 15 (79 %) children. CONCLUSIONS: Open mixed nut challenge can efficiently exclude multiple tree nut allergies in children with a lifelong nut free diet and low suspicion of clinical allergy.

[Hereditary fructose intolerance]. / Hereditaire fructose-intolerantie.

BACKGROUND: Hereditary fructose intolerance (HFI) is a rare metabolic disease affecting fructose metabolism. After ingestion of fructose, patients may present with clinical symptoms varying from indefinite gastrointestinal symptoms to life-threatening hypoglycaemia and hepatic failure. CASE DESCRIPTION: A 13-year-old boy was referred to the department of metabolic diseases because of an abnormal fructose loading test. He was known with persistent gastrointestinal symptoms since infancy. His dietary history revealed an avoidance of fruit and sweets. Because malabsorption was suspected, an oral fructose loading test was performed. During this test, he developed severe vagal symptoms which were probably caused by a potentially fatal hypoglycaemia. The diagnosis of HFI was confirmed by genetic analysis. CONCLUSION: A good dietary history may be of important help in the diagnosis of HFI. On suspicion of HFI, genetic analysis is easy and the first choice in the diagnostic work-up. With timely diagnosis and adequate dietary treatment patients have an excellent prognosis. Fructose loading tests as part of the diagnostics can be dangerous.

Factors related to high and low levels of drug adherence according to patients with type 2 diabetes.

OBJECTIVE: Adherence to medication in patients with type 2 diabetes varies widely, yet the factors that influence adherence according to patients are not fully known. The aim of this study is to explore both factors related to high and lower levels of adherence that patients with type 2 diabetes experienced in their medication use. SETTING: Primary care in the Netherlands. METHOD: Qualitative, semi-structured interviews were performed in 20 patients with type 2 diabetes. Interviews were audio-taped and transcribed verbatim. Transcripts were coded and analysed using content analysis and constant comparison. Main outcome measure experiences and opinions of patients concerning factors related to high and lower levels of adherence. RESULTS: Comparable aspects influenced drug adherence in more and less adherent patients. Four aspects that influenced adherence to medication emerged from the interviews: (1) information about the prescribed medication, (2) experience with medication and complications with use, (3) social support for medication behaviour and (4) routines in medication behaviour. Experience with medication and social support for medication behaviour were related to high levels of adherence in some patients, and to lower levels of adherence in others. Complicated medication regimens were mainly related to lower adherence, while social support and routines in medication behaviour were related to higher adherence. CONCLUSIONS: Routines in medication behaviour were related to higher drug adherence. Patient education should not only address information about the disease and medication, but also more practical issues concerning drug intake. Hence, to improve drug adherence in patients with type 2 diabetes, pharmaceutical care might be aimed at the counselling of patients to organise drug use in their daily schedule.